Epstein-barr virus latent membrane protein 1 induces and causes release of fibroblast growth factor-2

We have shown that the EBV oncoprotein, latent membrane protein 1 (LMP1), induces a constellation of tumor-invasiveness factors. Fibroblast growth factor (FGF)-2 is angiogenic as well mitogenic. Although FGF-2 does not contain a hydrophobic signal sequence for secretion, FGF-2 is released extracellularly. However, the mechanism by which FGF-2 is released is unclear. Here we show first that LMP1 induces in epithelial cells the expression of FGF-2 mRNA and protein through both LMP1 COOH-terminal activation domains, CTAR 1 and CTAR 2, which can activate nuclear factor (NF)-kappaB signaling and also the p38 mitogen-activated protein kinase pathway. Coexpression of IkappaBalpha (S32A/S36A), which cannot be phosphorylated and prevents NF-kappaB activation, with LMP1 inhibited induction of FGF-2 by LMP1, which suggests that LMP1 induces FGF-2 via NF-kappaB signaling. Moreover, unlike phorbol 12-myristate 13-acetate LMP1 also induced the release of the M(r) 18,000 isoform of FGF-2 protein. Transfection of Ad-AH cells with LMP1 deletion mutants lacking either CTAR 1 or CTAR 2 also induced the release of the protein. Secretion was confirmed in 293 cells, which do not contain detectable endogenous FGF-2 protein, cotransfected with FGF-2 and LMP1. Finally, Na(+)/K(+)-ATPase participates in FGF-2 release, independently of the classical endoplasmic reticulum/Golgi pathway. In this study, the release of M(r) 18,000 FGF-2 protein was partially suppressed by ouabain, which inhibits the activity of Na(+)/K(+)-ATPase alpha1 subunit, but not by Brefeldin A, which inhibits the endoplasmic reticulum/Golgi-dependent secretory pathway. In contrast, the release of M(r) 18,000 FGF-2 protein was almost completely inhibited by IkappaBalpha (S32A/S36A). These results suggest that FGF-2 release is independently mediated by NF-kappaB signaling, not simply a consequence of induction itself. Thus, NF-kappaB signaling is involved in induction of expression and release of FGF-2 by LMP1.     

Impairment of Na(+),K(+)-ATPase in CD95(APO-1)-induced human T-cell leukemia cell apoptosis mediated by glutathione depletion and generation of hydrogen peroxide.

Human T-cell leukemia is a malignant disease that needs various regimens of cytotoxic chemotherapy to overcome drug resistance. Recently, Na(+),K(+)-ATPase has emerged as a potential target for cancer therapy. However, its exact signaling pathway in human T-cell leukemia cell death has not been well defined. In the current study, we found CD95(APO-1) was able to trigger the internalization of plasma membrane Na(+),K(+)-ATPase in Jurkat cells or primary T cells as a mechanism to suppress its activity. This internalization was closely relevant to intracellular glutathione (GSH) depletion in Jurkat cells downstream of Fas-associated death domain protein (FADD) and caspase 8. GSH depletion in Fas L-treated Jurkat cells induced the generation of hydrogen peroxide (H(2)O(2)), which subsequently increased the serine phosphorylation of Na(+),K(+)-ATPase alpha1 subunit. Exogenous H(2)O(2) even mimicked the effect of Fas L to upregulate the serine phosphorylation of Na(+),K(+)-ATPase alpha1 subunit and suppress Na(+),K(+)-ATPase activity. Overall, our results indicate that CD95(APO-1) induces the FADD- and caspase 8-dependent internalization of Na(+),K(+)-ATPase through intracellular GSH loss, and the subsequent generation of H(2)O(2)-mediated serine phosphorylation of Na(+),K(+)-ATPase alpha1 subunit. Taken together, this study presents a novel regulatory mechanism of Na(+),K(+)-ATPase in CD95(APO-1)-mediated human T-leukemia cell apoptosis.     

The release of fibroblast growth factor-1 from melanoma cells requires copper ions and is mediated by phosphatidylinositol 3-kinase/Akt intracellular signaling pathway

Melanoma is a highly invasive tumor with elevated mortality rates. Progression and aggressiveness appear related to the achievement of an angiogenic phenotype. Melanoma cells express several angiogenic factors, including fibroblast growth factor (FGF)-1 and FGF-2. The autocrine production and release of FGFs and the subsequent activation of FGF receptors, have a central role in melanoma tumor progression. We demonstrated that FGF-1 is secreted from a human melanoma cell line, A375, under conditions of serum deprivation. The release of FGF-1 is inhibited by the copper chelator ammonium tetrathiomolybdate, suggesting a role of copper in the secretory pathway, and is triggered by activation of phosphatidylinositol 3-kinase (PI3K)/Akt intracellular signaling. Interestingly, overexpression or activation of Akt has been correlated with poor prognosis in melanoma patients. Our data indicate a novel role for Akt in supporting the progression of human melanomas and advocate the need for new treatments targeting PI3K/Akt signaling pathway, to control tumor development and progression.     

Role of the Na+, K(+)-adenosine triphosphatase in the accumulation of cis-diamminedichloroplatinum(II) in human ovarian carcinoma cells.

We examined the importance of the Na+, K(+)-ATPase in cisplatin (DDP) accumulation in 2008 human ovarian carcinoma cells and describe changes in the Na+, K(+)-ATPase in DDP-resistant cells with DDP accumulation defects. Approximately 50% of DDP accumulation was inhibitable by ouabain. DDP accumulation into 2008 cells could be maximally inhibited when cells were preincubated with ouabain for 1 h prior to DDP exposure. The half-maximal inhibition was obtained with 0.13 microM ouabain. Similar inhibition of DDP accumulation was obtained when the Na+, K(+)-ATPase was blocked by ATP depletion or by incubating cells in K(+)-free medium. This same percentage of DDP accumulation was Na+ dependent and varied directly with Na+ concentration. These effects on DDP accumulation could be detected as early as 1 min after the imposition of 0-trans conditions, strongly suggesting that the inhibition was due to modulation of a drug influx step. The Na+, K(+)-ATPase in 2008/DDP cells had a similar KD for ouabain binding and 36% less Na+, K(+)-ATPase molecules/mg of protein than 2008 cells. 2008/DDP cells 2.3 +/- 0.2 (SE, n = 3) fold cross-resistant to ouabain in a continuous exposure clonogenic assay. Despite these changes in the Na+, K(+)-ATPase, the net basal Na+, K(+)-ATPase activity was the same in sensitive and DDP-resistant cells as determined by ouabain-inhibitable 86Rb+ influx. The basal Na+ levels were also similar in the sensitive and resistant cells. These data suggest that DDP accumulation is partially Na+ dependent and that, therefore, the Na+, K(+)-ATPase which maintains the Na+ gradient may play an important role in determining how much DDP enters cells. Whether there is a causal link between the changes in the Na+, K+-ATPase in DDP-resistant cells and their DDP accumulation defect is not yet known.     

骨肉瘤外泌体miR-21通过调控PI3K/AKT通路促进骨肉瘤细胞侵袭及血管生成北大核心

目的:探讨骨肉瘤外泌体miR-21对骨肉瘤细胞侵袭能力的影响以及对血管生成的作用机制。方法:qRT-PCR法检测人正常骨细胞hFOB1.19与人骨肉瘤细胞系U2OS、Saos-2和MG-63中miR-21的表达,并确定表达水平高的作为本研究细胞系。通过差速离心提取细胞外泌体,并采用透射电镜和Western blot鉴定该外泌体;通过免疫荧光染色检测外泌体能否进入人血管内皮细胞(human vascular endothelial cells,HUVEC)发挥作用;利用脂质体2000分别转染Control、miR-21-inhibitor以及miR-21-mimic,通过Transwell实验检测外泌体miR-21对U2OS细胞侵袭能力的影响,并进一步采用Western blot检测miR-21对血管相关蛋白VEGF、HIF-1α以及PI3K/AKT通路蛋白的影响。结果:人骨肉瘤细胞系Saos-2、MG-63和U2OS中miR-21均呈高表达。透射电镜观察到,外泌体呈圆形或椭圆形泡状结构,且其特征蛋白CD9、CD63和CD81蛋白在外泌体中较U2OS细胞中表达高。免疫荧光结果显示,U2OS外泌体能成功进入HUVEC细胞中发挥作用。Transwell实验结果表明,外泌体miR-21可以促进骨肉瘤细胞侵袭。Western blot结果表明,与Control组相比,miR-21-mimic组血管生成蛋白VEGF和HIF-1α表达水平显著上升,PI3K/AKT通路蛋白表达水平亦显著升高,差异均有统计学意义(P<0.05)。结论:U2OS外泌体miR-21可以促进骨肉瘤细胞侵袭和血管生成,其作用机制可能与miR-21进入细胞激活PI3K/AKT信号通路有关。     

Human tumor cell sensitivity to oleandrin is dependent on relative expression of Na+, K+ -ATPase subunitst

The membrane enzyme Na+, K+ -ATPase is known to help maintain ion homeostasis in mammalian cells. Newly identified functions of this enzyme suggest that inhibition of Na+, K+ -ATPase by cardiac glycosides may be useful to patients with cancer. Twelve human tumor cell lines were chosen to examine determinants of human tumor cell sensitivity to cardiac glycosides. In vitro cell culture models of human glioma HF U251 and U251 cells as well as human parental and modified melanoma BRO cells were also included in these studies. Data derived from both models and twelve tumor cell lines indicated that high expression of Na+, K+ -ATPase alpha 1 isoform in the presence of low alpha 3 expression correlated with increased resistance to inhibition of cell proliferation by cardiac glycosides such as oleandrin, ouabain and bufalin. Interestingly, increased expression of Na+, K+ -ATPase alpha 1 and therefore total Na+, K+ -ATPase activity is associated with increased cellular levels of glutathione. The altered enzyme activity and glutathione content were associated with a delayed and diminished release of cytochrome c and caspase activation. Additionally, an increased colony-forming ability was noted in cells with high levels of Na+, K+ -ATPase alpha 1 expression, suggesting that Na+, K+ -ATPase alpha 1 isoform may be actively involved in tumor growth and cell survival. Its inhibition by cardiac glycosides may provide a strategy for effective cancer therapy.     

Modulation of thyroid hormone-dependent Na+,K(+)-ATPase induction in cultured human submandibular gland cell lines, HSG cells

The hormonal regulation of Na+,K(+)-ATPase enzyme activities and induction of the alpha subunit protein of the enzyme in the human submandibular gland (HSG) were studied by use of cultured HSG cells. We treated HSG cells with thyroid hormone, androgen, mineralocorticoid, and glucocorticoid, singly or in combination. 3,5,3'-Triiodothyronine (T3), 5 alpha-dihydrotestosterone (DHT), and aldosterone (Ald) induced neither Na+,K(+)-ATPase enzyme activity nor its protein. On the other hand, dexamethasone (Dex) induced both Na+,K(+)-ATPase enzyme activity and the alpha subunit protein level to 128% of the control. The effects of Dex in combination with either T3 or DHT were similar to the effect of Dex alone. Treatment in combination with Dex and Ald increased the enzyme activity and alpha subunit protein level to 160%, synergistically. These increased Na+,K(+)-ATPase enzyme activities were shown to be dependent on their protein levels induced by the hormones. Contrary to the previous evidence that Na+,K(+)-ATPase of ducts in the salivary gland are thyroid hormone inducible, HSG cells had an insignificant response to thyroid hormone in the present study. Also, Na+,K(+)-ATPase enzyme activity and its alpha subunit protein were not induced by any kind of combined treatments with T3. Furthermore, T3 did not cause intracellular calcium mobilization in HSG cells. In view of all data taken together, we suggest that HSG cells lack the thyroid hormone receptor, which is necessary for Na+,K(+)-ATPase induction in human salivary gland.     

Na+/K+-ATPase α3 mediates sensitivity of hepatocellular carcinoma cells to bufalin

Bufalin, a major bioactive component of the Chinese medicine Chansu, has been reported to exhibit significant antitumor activity against various cancer cell lines. However, the exact mechanism remains unclear. In this study, we demonstrated that bufalin inhibited the growth of hepatocellular carcinoma (HCC) cells in a dose-dependent manner, which correlated with the expression level of Na+/K+-ATPase α3 in HCC cells. The IC50 of bufalin markedly increased when Na+/K+-ATPase α3 was silenced by RNA interference. Furthermore, we show that bufalin increased the phosphorylation of Akt and ERK1/2 while inhibited FoxO3a expression. Thus, our study suggests that Na+/K+-ATPase α3 might serve as a therapeutic target for bufalin in HCC, and its expression status may help predict sensitivity of HCC cells to bufalin treatment.     

Identification and prevalence of CD8(+) T-cell responses directed against Epstein-Barr virus-encoded latent membrane protein 1 and latent membrane protein 2

Epstein-Barr virus (EBV) is associated with several human malignancies that each show different viral gene expression profiles. In malignancies such as Hodgkin's disease and nasopharyngeal carcinoma only Epstein-Barr nuclear antigen 1 (EBNA1) and varying levels of latent membrane proteins 1 and 2 (LMP1 and -2) are expressed. Since endogenously expressed EBNA1 is protected from CTL recognition, LMP1 and LMP2 are the most likely target antigens for anti-tumor immunotherapy. Therefore, we sought to identify in a systematic way CD8(+) T-cell responses directed against eptitopes derived from LMP1 and LMP2. Using IFNgamma-ELISPOT assays of interferon-gamma release, peripheral blood mononuclear cells (PBMC) of healthy donors were screened with peptide panels (15 mer overlapping by 10) spanning the LMP1 and LMP2 sequences of the prototype EBV strain B95.8. When positive responses were found, CD4(+) or CD8(+) T cells were depleted from donor PBMC to determine the origin of the responder population. We detected CD8(+) T-cell responses to LMP1 in 9/50(18%) donors and to LMP2 in 15/28 (54%) donors. In addition to the already described epitopes, 3 new LMP1- and 5 new LMP2-derived CD8(+) epitopes were identified. In most donors LMP1- and LMP2-specific CD8(+) precursor frequencies were low compared with precursors against immunodominant EBV epitopes from latent (EBNA3A, -3B and -3C) and lytic cycle antigens. These results demonstrate that CD8(+) memory T cell responses to LMP1 and especially to LMP2 do exist in Caucasians, albeit at low levels and could potentially be exploited for therapeutic use.     

食管鳞癌细胞外泌体中miR-130a对血管新生的作用及其机制

目的 探讨食管鳞癌细胞外泌体中的miR-130a对血管新生的作用及其机制。方法 提取食管上皮细胞HEEC、食管鳞癌细胞TE-13和Eca-109所分泌的外泌体及转染miR-130a mimic、miR-130a inhibitor及其阴性对照（NC）后的Eca-109细胞外泌体,并与人脐静脉血管内皮细胞HUVEC共孵育。采用MTT、Transwell小室及小管形成实验检测各组HUVEC细胞的增殖、迁移和小管形成能力,qRT-PCR检测miR-130a的表达水平,Western blot检测PI3K和AKT的磷酸化水平以及PTEN、Ang1和iNOS的表达水平。结果 HUVEC细胞与TE-13、Eca-109细胞外泌体共孵育后,增殖、迁移以及小管形成能力均增强（P＜0.01）,PI3K与AKT磷酸化水平及Ang1与iNOS的表达水平上调（P＜0.001）,而PTEN表达水平下调（P＜0.001）。qRT-PCR检测结果显示,TE-13和Eca-109细胞外泌体中的miR-130a表达水平均高于HEEC细胞（P＜0.01）。下调Eca-109细胞外泌体中的miR-130a表达可抑制HUVEC细胞增殖、迁移及小管形成能力（P＜0.01）,同时下调PI3K和AKT的磷酸化及Ang1和iNOS表达水平（P＜0.001）,上调PTEN表达水平（P＜0.001）。结论 食管鳞癌细胞外泌体中的miR-130a可能通过激活血管内皮细胞的PTEN/PI3K/AKT信号通路诱导肿瘤血管新生。     

Oxidative stress reduces Na+/H+ exchange (NHE) activity in a biliary epithelial cancer cell line (Mz-Cha-1)

In cholangiocarcinogenesis, chronic inflammation and oxidative stress play a key role. The Na(+)/H(+) exchanger (NHE) forms a potential link between control of intra- and pericellular pH and tumor development. Therefore, the effects of oxidant stress were determined by the use of tert-butyl hydroperoxide (t-BOOH) on Na(+)/H(+) exchange in a biliary epithelial cancer cell line (Mz-Cha-1). The cells were exposed to the hydroperoxide and the rate of recovery from acidosis was determined by the use of the pH-sensitive fluorochrome 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein acetoxymethyl ester (BCECF/AM). t-BOOH reduced Na(+)/H(+) exchange activity in a dose-dependent manner. At 4 mM t-BOOH, Na(+)/H(+) exchange activity was virtually absent. This was accompanied by an increase in cytotoxicity (MTT assay). Glutathione repletion and intracellular Ca(++) chelation partially restored the Na(+)/H(+) exchange activity. Hydroperoxide seemed neither to alter the intracellular signal transduction pathways (cAMP and Ca(++) oscillations) nor the membrane distribution of the exchanger (immunostaining). Decrease in Na(+)/H(+) exchange activity in this model of oxidant stress may represent an early perturbation of membrane function, and the functional integrity of Na(+)/H(+) exchange could therefore be dependent on the glutathione redox system.     

Downregulation of intracellular nm23-H1 prevents cisplatin-induced DNA damage in oesophageal cancer cells: possible association with Na(+), K(+)-ATPase

Previously, we showed that expression of nm23-H1 is associated inversely with sensitivity to cisplatin in human oesophageal squamous cell carcinoma (OSCC). The present study was undertaken to investigate the association of nm23-H1 expression with cisplatin-induced DNA damage in OSCC using antisense nm23-H1 transfectants. YES-2/AS-12, an antisense nm23-H1-transfected OSCC cell line, showed significantly reduced expression of intracellular nm23-H1 protein compared with that in parental YES-2 cells and YES-2/Neo transfectants. Surface expression of nm23-H1 protein was not observed in any of the three cell lines. PCR analysis for DNA damage demonstrated that YES-2/AS-12 cells were more resistant to nuclear and mitochondrial DNA damage by cisplatin than were YES-2/Neo cells. In addition, mitochondrial membrane potentials and DNA fragmentation assays confirmed that YES-2/AS-12 was more resistant than YES-2/Neo to apoptosis induced by cisplatin. In contrast, YES-2/AS-12 was more sensitive to ouabain, a selective inhibitor of Na(+), K(+)-ATPase, than YES-2 and YES-2/Neo. Pre-treatment with ouabain resulted in no differences in cisplatin sensitivity between the three cell lines examined. Intracellular platinum level in YES-2/AS-12 was significantly lower than that in YES-2 and YES-2/Neo following incubation with cisplatin, whereas ouabain pre-treatment resulted in no differences in intracellular platinum accumulations between the three cell lines. Our data support the conclusion that reduced expression of intracellular nm23-H1 in OSCC cells is associated with cisplatin resistance via the prevention of both nuclear and mitochondrial DNA damage and suggest that it may be related to Na(+), K(+)-ATPase activity, which is responsible for intracellular cisplatin accumulation.     

EBV‐encoded LMP1 regulates Op18/stathmin signaling pathway by cdc2 mediation in nasopharyngeal carcinoma cells

Oncoprotein 18/stathmin (Op18/stathmin) plays a crucial role in maintaining cell biological characteristics by regulating microtubule dynamics, especially entry into mitosis; phosphorylated Op18/stathmin promotes microtubule polymerization to form the mitotic spindle, which is essential for chromosome segregation and cell division. Cdc2 is a critical kinase in starting M phase events in cell‐cycle progression and is a positive regulator of the cell cycle. Latent membrane protein 1 (LMP1) is an Epstein‐Barr virus (EBV)‐encoded oncogenic protein that is able to induce carcinogenesis via various signaling pathways. This study focused on regulation by LMP1 of Op18/stathmin signaling in nasopharyngeal carcinoma (NPC) cells and showed that LMP1 regulates Op18/stathmin signaling through cdc2 mediation, LMP1 upregulates cdc2 kinase activity, and Op18/stathmin phosphorylation promotes the interaction of cdc2 with Op18/stathmin and microtubule polymerization during mitosis, and inhibition of LMP1 expression attenuates the interaction of cdc2 and Op18/stathmin and promotes microtubule depolymerization. These results reveal a new pathway via which LMP1 regulates Op18/stathmin signaling by cdc2 mediation; this new signaling pathway not only perfects the LMP1 regulation network but also elucidates the molecular mechanism of LMP1 that leads to carcinogenesis. © 2008 Wiley‐Liss, Inc.     

缺氧诱导的结直肠癌外泌体通过激活PTEN/PI3Kγ信号通路介导巨噬细胞极化

目的:探究缺氧条件下,结直肠癌细胞外泌体对巨噬细胞极化的影响及机制。方法:差速离心法提取正常条件下和缺氧条件下结直肠癌细胞HT-29所分泌的外泌体（HT-29 N-exo和HT-29 H-exo）,透射电镜和Western blot鉴定外泌体,荧光显微镜下观察外泌体的摄取。将U937细胞与100 ng/mL的PMA共孵育的同时分别与1 μg/mL的HT-29 N-exo和HT-29 H-exo以及等体积的PBS共孵育,记为PBS组、HT-29 N-exo组、HT-29 H-exo组。qRT-PCR检测各组细胞CD163、IL-10、IL-1Rα、TGF-β1、CCL2、TNF-α mRNA的表达,Elisa检测各组细胞IL-10 和 TNF-α 分泌,流式细胞术鉴定各组细胞CD163和CD11b表达,Western blot检测各组细胞PTEN/PI3Kγ信号通路激活情况。结果:差速离心法所提取的外泌体符合其结构和生物学特征,并且可被U937细胞摄取;相比于HT-29 N-exo组, HT-29 H-exo组细胞CD163、IL-10、IL-1Rα、TGF-β1、CCL2表达显著增加（P＜0.05）,IL-10分泌显著增加,TNF-α 表达以及分泌显著减少（P＜0.01）,CD163+CD11b+巨噬细胞数显著增加（P＜0.001）,PTEN/PI3Kγ信号通路显著激活（P＜0.001）。结论:缺氧条件下结直肠癌细胞外泌体能够显著促进巨噬细胞M2型极化,其机制为激活PTEN/PI3Kγ信号通路。     

哇巴因抑制结直肠癌多药耐药细胞增殖及侵袭力的研究

  目的  探讨结直肠癌耐药细胞增殖及侵袭力与Na+, K+-ATP酶活性及其β1亚单位和P糖蛋白(P-gp)表达的关系, 及哇巴因增加化疗敏感性的可能机制。  方法  以人结直肠癌亲本细胞(SW480)和耐奥沙利铂细胞(SW480/OxR)为研究对象, 采用MTS法、Transwell小室、生化酶学、实时定量PCR(Real time quantitative, RT-PCR)及流式细胞技术等方法比较SW480细胞与SW480/OxR细胞的增殖及侵袭力、Na+, K+-ATP酶活性及其β₁亚单位和P-gp表达的差异, 观察哇巴因对SW480/OxR细胞上述指标的影响。  结果  与SW480细胞比较, SW480/OxR细胞增殖活力无明显变化(P > 0.05), 而细胞侵袭力却显著增加, Na+, K+-ATP酶活性下降, β₁亚单位表达下调, P-gp表达上调(P均 < 0.01);哇巴因能显著抑制SW480/OxR细胞增殖活力, 减弱其侵袭力, 下调SW480/OxR细胞P-gp蛋白表达, 上调SW480/OxR细胞β₁亚单位蛋白表达, 增加SW480/OxR细胞Na+, K+-ATP酶活性(P均 < 0.01)。  结论  Na+, K+-ATP酶活性下降可能源于β₁亚单位表达下调, 并参与结直肠癌的耐药; 哇巴因能部分逆转结直肠癌耐药细胞MDR, 可能与增加Na+, K+-ATP酶活性及下调P-gp表达有关。      

EBV latent membrane protein 1 effects on plakoglobin, cell growth, and migration

Latent membrane protein 1 (LMP1), the major oncoprotein of EBV, is likely responsible for many of the altered cellular growth properties in EBV-associated cancers, including nasopharyngeal carcinoma (NPC). In this study, the effects of LMP1 on cell growth and migration were studied in the context of the EBV-positive C666-1 NPC cell line. In the soft agar transformation and Transwell metastasis assays, LMP1 enhanced cell growth and migration through activation of phosphatidylinositol 3-kinase (PI3K)/Akt and nuclear factor-kappaB (NF-kappaB) signaling. Inhibitors of PI3K, Akt, and NF-kappaB signaling dramatically reduced these enhanced properties. An IkappaBalpha super-repressor also blocked these effects. However, constitutive activation of Akt alone did not alter cell growth, suggesting that both PI3K/Akt and NF-kappaB activation are required by LMP1. These enhanced effects required the full-length LMP1 encompassing both the PI3K/Akt-activating COOH-terminal activation region (CTAR) 1 and the nonredundant NF-kappaB-activating regions CTAR1 and CTAR2. LMP2A, a latent protein that is also frequently expressed in NPC, similarly activates the PI3K/Akt pathway; however, its overexpression in C666-1 cells did not affect cell growth or migration. LMP1 also decreased expression of the junctional protein plakoglobin, which was shown to be partially responsible for enhanced migration induced by LMP1. This study reveals that in epithelial cells the transforming properties of LMP1 require activation of both PI3K/Akt and NF-kappaB and shows that the loss of plakoglobin expression by LMP1 is a significant factor in the enhanced migration.     

LMP1 and LMP2 may be Prognostic Factors for Outcome ofTherapy in Nasopharyngeal Cancers in Indonesia

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy that is invasive and metastasizes easily. Inseveral Asian countries it is the most commonly found of the head and neck malignancies. Epstein Barr virus(EBV) infection is one of the agents causing NPC, so that expression of LMP1 and LMP2 may affect the outcomeof therapy, metastasis, recurrence, and survival of NPC patients. This study aimed to investigate their expressionin relation to therapy outcome and survival in a series of Indonesian NPC patients. The methods used werenested case control and Kaplan-Meier survival analysis. Differences in therapy outcome in relation to LMP1and LMP2 expression were analyzed through chi square statistics. As a result, in post treatment NPC, there wasa significant difference in therapy outcome between LMP2 (+) compared to LMP2 (-) (P = 0.001). There wasalso a significant difference in 24-months-survival between NPCs expressing LMP1 (+) or LMP2 (+) comparedto those expressing LMP1 (-) or LMP2 (-).